Ind. Code § 8-1-2-53
Any public utility receiving from the commission any blanks, with directions to fill the same, shall cause the same to be properly filled out so as to answer fully and correctly each question therein propounded, and, in case it is unable to answer any question, it shall give a good and sufficient reason for such failure, and said answers shall be verified under oath by the president, secretary, superintendent or general manager or person in charge of such public utility and returned to the commission at its office within the period fixed by the commission. Whenever required by the commission, every public utility shall deliver to the commission for examination any or all maps, profiles, contracts, reports of engineer and all documents, books, accounts, papers and records, or copies of any or all of the same, with a complete inventory of all its property in such form as the commission may direct.
IC 8-1-2-53